Monthly Archives: December 2013

No, no, FBI is not in the storage business and there are no witnesses to protect.

However, SMB 3.0 has introduced a RPC-based mechanism to inform the clients of any state change in the SMB servers. Microsoft calls it Service Witness Protocol [SWP], and its objective is provide a much faster notification service allow the SMB 3.0 clients to do a failover. In previous SMB 1.0 and even in SMB 2.x, the SMB clients rely on time-out services. The time-out services, either SMB or TCP, could take up as much as 30-45 seconds, and this creates a high latency that is disruptive to enterprise applications.

SMB 3.0, as mentioned in my previous post, had a total revamp, and is now enterprise ready. In what Microsoft calls “Continuously Available” File Service, the SMB 3.0 supports clustered or scale-out file servers. The SMB shares must be shared as “Continuously Available” shares and mapped to SMB 3.0 clients. As shown in the diagram below (provided by SNIA’s webinar),

Client A mapping to Server 1 share (\\srv1\CAshr). Client A has a share “handle” that establishes a connection with a corresponding state of the session. The state of the session is synchronously kept consistent with a corresponding state in Server 2.

The Service Witness Protocol is not responsible for the synchronization of the states in the SMB file server cluster. Microsoft has left the HA/cluster/scale-out capability to the proprietary technology method of the NAS vendor. However, SWP regularly observes the status of all services under its watch. Continue reading →

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I am one of the guilty parties who continues to use CIFS (Common Internet File System) to represent the Windows file sharing protocol. And a lot of vendors continue to use the “CIFS” word loosely without knowing that it was a something from a bygone era. One of my friends even pronounced it as “See Fist“, which sounded even funnier when he said it. (This is for you Adrian M!)

And we couldn’t be more wrong because we shouldn’t be using the CIFS word anymore. It is so 90’s man! And the tell-tale signs have already been there but most of us chose to ignore it with gusto. But a recent SNIA Webinar titled “SMB 3.0 – New opportunities for Windows Environment” aims to dispel our incompetence and change our CIFS-venture to the correct word – SMB (Server Message Block).

A selfie photo of Dennis Chapman, Senior Technical Director for Microsoft Solutions at NetApp from the SNIA webinar slides above, wants to inform all of us that … Continue reading →